Variable displacement pump and pressure responsive control means therefor



March 24, 1959 B. E. o'coNNoR ETAL 2,878,755

VARIABLE DISPLACEMENT PUMP AND PRESSURE RESPONSIVE CONTROL MEANSTHEREFOR Filed May 15 1950 A2 Sheets-Sheet l gw l, l

March 24, 1959 B. E. o'coNNoR ErAL 2,878,755

VARIABLE DISPLACEMENT PUMP AND PRESSURE RESPONSIVE CONTROL MEANSTHEREFOR Filed May 13, 1950 2 Sheets-Sheet 2 United States Patent OVARIABLE DEPLACEMENT PUMP AND PRES- URE RESPONSIVE CONTROL MEANS THERE-Bernard E. UConnor, Buffalo, and Alfred G. French, East Aurora, N.Y.,assignors to Houdaille Industries, Inc., Detroit, Mich., a corporationof Michigan Application May 13, 1950, Serial No. 161,754

Claims. (Cl. 1031-120) The present invention relates to improvements invariable displacement pumps and is `more particularly concerned withnovel structure and relationships in such pumps for contro-lling pumpdisplacement.

An important object' of the present invention is to provide improvementsin variable displacement `pumps for automatically as well as selectivelyadjusting pump displacement.

Another object of the invention is to provide improved means forcontrolling variable displacement pumps responsive to pump-createdpressure and selectively adjustable for varying the pump pressureresponsiveness thereof.

A further object of the invention is to provide novel pressureresponsive control valve means and means for selective modification ofits pressure responsiveness for controlling the displacement of avariable displacement pump.

Yet another object of the invention is to provide improved control valvemeans for variable displacement pumps normally responsive topredetermined pumpcreated pressure above a mean pressure to maintain thepressure substantially constant by varying the pump displacement, andincluding means controllable from a point externally of the pump to varythe pressure responsiveness of the valve means.

Still another object of the invention is to improve the generalconstruction of variable displacement pumps.

Other objects, features and advantages of the present invention will bereadily apparent from the following detailed description of a preferredembodiment thereof taken in conjunction with the accompanying drawings,in which:

Figure 1 is an elevational view of one side of a variable displacementpump of a type especially suitable for use in a transmission for anautomotive vehicle or the like;

Figure 2 is a sectional detail view taken substantially on the lineII--II of Figure l through the face plate of the pump assembly shown infull in Figure l;

Figure 3 is a side elevational view of the opposite side of the pumpfrom that shown in Figure l and with the face plate removed to revealinternal mechanism of the pump; and

Figure 4 is a sectional detail view taken on substantially the lineIV-IV of Figure l.

By way of illustration there is shown in the drawings a variabledisplacement pump of the sliding vane type and in the particularembodiment shown adapted for use in the transmission system of anautomotive vehicle. The pump comprises a casing housing a pump rotor 11which has a uniformly spaced series of radial peripherally opening slots12 within which are operably disposed sliding reciprocable vanes 13. Thesides of the rotor 11 are inset at predetermined distance from itsperiphery at both sides to accommodate concentric rings 14 in engagementwith the inner ends of the vanes 13 and functioning to maintain'theouter ends of the vanes or blades on a predetermined diameter. A centralbore may be provided through the rotor 1l provided with spline teeth 15by which the'rotor is adapted to be assembled for rotation upon asplined shaft in a transmission assembly.

A circular pump chamber 17 concentric with the control rings 14 and of adiameter to be constantly engaged by the outer tips of the vanes 13 isprovided by a displacement control member or modulator 18. In thepresent instance the modulator 18 is of the reciprocablyv guided typehaving opposite parallel at sides or edges 19 slidably engaging parallelbearing walls 20 defining opposite sides of a modulator control chamber21 provided in an intermediate casing member or ring 22. By preferencethe housing ring 22, the modulator 18 and the rotor 11 are ofapproximately the same thickness, thatis their broad faces are disposedin approximately the saine planes while opposite facing plates 23 and 24complete the housing or casing -10 enclosing the pump and moreparticularly affording closures for the pump chamber 17 and themodulator chamber 21. In assembly, suicient sliding clearance isafforded for the pump rotor 11 and the modulator 18 after the facingplates 23 and 24 have been secured to the opposite faces of theintermediate casing member 22 so as to permit free rotation of the rotor11 and slidable reciprocation of the modulator ring 18.

As best seen in Figure 4, the facing plate 23 may be provided with acentral hollow hub 25 provided with internal splines 26 for connectionof a spline member in the transmission with which the unit may be used.A iiuid passage 27 leads from the splined bore to the outside of thecasing. The diameter of the spline bore iny the boss 25 may be smallerthan the diameter of the spline bore in the pump rotor 11. Clearancepassage for the shaft to which the pump rotor is splined is provided bya concentric bore 2S in the facing plate 24.

Rotation of the rotor 11 in operation is intended tol be clockwise asviewed in Figure 3 so that hydraulic liuid from any appropriate sourceis drawn through an arcuate inlet duct or port 29 by action of the rotorblades 13 at the low pressure side of the pump and displaced through anoutlet duct or port 30 at the high pressure side of the pump. Both ofthe ports 29 and 30 are preferably located in the inner face of thefacing plate.

23. As best seen in Fig. l, an inlet passage 31 leads-to the inlet port29 while a discharge or high pressurey passage 32 leads from the highpressure port 30.

At the beginning of operation, at least, it is desirable that the pumpdisplacement be at maximum, and for this purpose the modulator 18 ispreferably biased to dispose the pump chamber 17 in maximum eccentricpumping relation to the rotor 11 by a spring 33 which may be in the formof a coiled compression biasing spring seated at one end in a shallowdepression 34 in one end of the modulator and at its other end in asocket-like recess 3S in the opposing wall defining the modulatorchamber 21 in the intermediate casing ring 22.

The principal function of the biasing spring 33, which may be ofrelatively light weight and which need not be of any critical load orcompression strength, is to assure that the modulator 1S will normallybe, at least at the beginning of operation, in a position of pumpchamber eccentricity with respect to the pump rotor 11. As a result,when the pump is started, maximum displacement will occur.

Means are provided for automatically adjusting thev tically adjustablecontrol valve structure 37 (Figs. 1

and 2) operable to control the application of pump- Patented Mar. 24,1959 created pressure for directly adjusting the position of themodulator 18 within the modulator chamber 21 for establishing andmaintaining such a relationship of the pump chamber 17 to the pump rotor11 that amean pump o utput pressure selected,within a.variable range ismaintained `as desired;

In a convenient, economical and highlyr etiicient form the control valveassembly 37 includes a reciprocable plunger valve member 3S operativelyslidably disposed within a` bore 39 in the pump housing 1i), and in thepresent instance located in the facing plate 23 which for this, purposeis provided with a thickened portion or embossment 40 at one side of thehub 25. A salient advantage of such location of the valve bore 39resides in that all piping can be avoided for effecting communicationbetween the fluid system of the pump and the modulator chamber 21 by wayof the control valve. All such communication can thus be elected bypassages or ducts in the housing 10. This is a valuable feature wherespace isat a premium and a compact unit without external ducts, tubes orpiping is desired, such as in an automotive transmission. Thisarrangement also avoids the liability of accidental blockage orrestriction of the intercommunicating fluid passages as often occurs insysn tems including tubes serving as fluid passages and thus liable todamage during installation or servicing of the apparatus, or otherwise.Furthermore, frictional pressurelosses are greatly reduced because ofthe relatively more direct, short passage communications that can beattained through the ducts and bores providing uid passage within thewalls of the housing 10.

By preference, the control valve housing bore 39is so disposed thatdirect communication with the high pressure or discharge port of thepump is effective through alpassage bore 41 between the port 30 and oneend portionpofwthe valve bore 39. In this way the adjacent end of thevalve body 38 is subjected to pump pressure during operation. In orderto assure constant exposure of the mentioned endl of the valve member tothe high pressure, such end may -be provided with a reduced diameter orhead end stop finger 42 engageable with a closure plug 43 by whichtheproximate end of the valve bore 39 is sealed off outwardly from the highpressure communication duct 41.

The valve-member 38 is normally biased in opposition` to. pump pressure,that is toward the head end ofthe valve, by means herein comprising acoiled compression spring44 actngagainst the opposite or rear end of thevalve member and seated against a bottom or shoulder 45 at the inner endof the valve bore. For this purposi?,4 the length of the valve housingbore 39 is substantially longer than the body portion of the valvemember 38.` The spring 44 is selected both as to length and tensioningqualities to resist, under load, movement of the valve member 38 inopposition to the spring with a predetermined static force. Thus, untilthe dynamic pressure of the pump-impelled uid attains a force in excessof the spring loading, the valve38 will be maintained in its fullybiased position.

The relationship of the biasing spring 44 to the valve member 38 is suchthat when a mean pump output pressure value is exceeded, the pumppressure acting upon the head of the valve drives the valve inopposition to the spring for eiecting valve controlled communicationwith the modulator chamber 21 to effect shifting of the modulator andthus adjustment in the pump displacement and return to the mean outputpressure. For this purpose, communication is effected betweenappropriate portions of the valve bore 39 and the modulator chamber 21.`Since during acceleration of the pump at the beginning `of operation orduring operation at lower than the mean output pressure, itis desirableto have the modulator 18 in the position of maximum pump chambereccentricityprelative to the pump rotor 11, initial communicationbetween a sub-chamber 47 between the end of the modulator 18 engaged bythe biasing spring 33 and the opposing wall detining the modulatorchamber is effected with the high pressure side of the pump by way of aport or duct 48 (Figs. l, 2 and 4) leading from the valve bore 39 to arecess 49 in theperiphery of the facing plate 23 and communicating witha fluid passage channel .50 provided in the periphery of theintermediate housing member 22 running to a radially inwardly directedpassage Sll entering the modulator sub-chamber 47. A housing member 10aabout the casing 10 closes the rcces s49 and the channel 50. In thefullyV biased or at rest position of the valve member 38 an annulargroove 52 in the valve member registers with the passage 48, while aplurality of annularly spaced longitudinally extending bores 53 in thehead end portion of the valve member afford communication between thehead end of the valve member and the channel 52. Thus, pump-createdpressure less than and up to the mean pressure for which the valvemember 38 is biased will be eiected through the communication passagewayto the modulator sub-chamber 47 for acting on that end, namely thebiased end of the modulator to assist the biasing spring 33 inmaintaining the modulator in full eccentric position.

At the same time, all pressure is relieved from the opposite end of themodulator 18. At this end, the modulator is formed withy aattened stopportion 54 which engages a complementary flattened abutment portion 55defining part of the wall of the modulator chamber in the intermediatecasing member 22 (Fig. 3). l stop portion 54, the end portion of themodulator is recessed or set back' to provide a modulator sub-chamber57. A bore passage 58 communicates with the sub-chamber S7 and with thevalve bore 39 in a position to register with a peripheral annularcommunication groove 59 iu the valve member 38 communicatingby way oanannularly spaced set of longitudinal passages 60 with and through theend of the valve member 38 and thus with the biasing spring chamber inthe bore 39 behind the valve member. A port 61 effects communicationbetween the inner end portion of the valve chamber 39 and the lowpressure or suction port 29 of the pump fluid` system. Thus, meansare-provided in an eicient and simple manner for relieving the modulatorof pressure at the end toward which it is` biased while the pump lisoperating below a given mean operating pressure. It will be understood,of course, that preferred communication could be effected between the4sub-chamber 57 and atmosphere at a sump or thel like, since theprincipal consideration is pressure relief.

When the pump-created pressure has attained the desired mean the valvemember 38 is moved in opposition to the biasing spring 44 to a balancedposition wherein,

the valve member 38 closes off the ports or passages 48 and4 58. Thissubstantially locks the modulator 18 in its fully eccentric position.

Upon development'of pump `pressure in excess of the mean pressuredesired,4 the valve member 38 is moved additionally in opposition to thebiasing spring 44 until a pressure uid duct or port '62, which up tothis time has been closed by the valve 38, is `opened to the highpressure side of the pump by registration of the high.

pressure groove A52 in the4 valve with the port 62. The pressure port orpassage 62 communicates with the modulator sub-chamber 57 to exertpressure upon the contiguous end of the modulator 18 and shift themodulator toward a position of `less pump chamber eccentricity relativeto the rotor 11. At the same time pressurerelief communication with themodulatorsub-chamber 47 is eiiected by opening of a port onpassage 63upon registration of relief groove 59 in the valve member therewith to;effect communication with the recess 494 to which' thev passage 63leads.l Thus, the modulator is quickly shifted and the desired meanoutput pressure re-established, the

valve member 38 ,returning nto. a port blocking` position Adjacent the iagarrarse as 4soonI as the desired mean pressure has beenre-established.

It will thus be apparent that highly sensitive control automatically inresponse to pump-created pressure is afforded over the modulator 18 byresponse of the valve 38 to action of the biasing spring 44 and thedynamic pressure of the pump acting upon respective opposite ends of thevalve member.

To accommodate situations where in the course of operation it isnecessary to increase the mean pump output pressure during anyparticular interval, means are providedfor selectively imposing anincreased biasing pressure upon the valve member 38 in addition to andsupplemental to the biasing spring 44. To this end, a supplementarybiasing plunger element or member 64 is slidably Vdisposed within areduced diameter inward extension 65 fromv the valve bore 39 andconcentric with the valve bore. Valve biasing engagement with the valvemember 38 by the biasing plunger 64 is elTected through the medium of arearwardly extending projection or stem 67 on the valve member directedinto the spring 44.

When the control valve 38 is to function solely under the biasinginuence of the spring `44, the auxiliary biasingplungery 64 remainsinert or free floating in the bore extension 65. However, when it isdesired to increase the ybias upon the valve 38, fluid under pressure isintroduced into the bore portion 65 through a passage 68 leading into afurther reduced diameter portion or port 69 at the rear of the reducedbore portion 65. The passage 68 leads off through the casing face plate23 and if desiredv onfthroug'h the outer housing or supporting membery aand communicates with any preferred source of uid under pressure whichmay be a separate source of fluidor may be the pressure uid displaced bythe pump. In any event, any preferred additional biasing load may beimposed upon the valve 38 by the fluid pressure introduced behind thebiasing plunger 64. For example, if the biasing spring 44 is rated at aloading of thirty pounds per square inch resistance to the valve 38, andit is desired to establish a mean pump output pressure of sixty poundsper square inch, then the pressure introduced behind the biasing plunger64 will be sixty pounds per square inch. Of course, it will be clearthat any other selected or additional pressure desired may be imposedupon the valve 3S through the plunger 64 by imposing the desiredauxiliary biasing uid pressure upon the auxiliary biasing plunger 64.

The stem extension 67 of the valve member 38 also serves as a stop forlimiting rearward or pressure induced movement of the valve member 38,so that under unusual pressure thrusts the valve member will not overrunthe system of control ports leading to the modulator chamber.Accordingly, at the limit of pressure thrust movement of the valvemember, the auxiliary plunger 64 comes to rest against a stop shoulder70 provided at the bottom of the auxiliary reduced diameter auxiliaryplunger bore 65. In this thrust limit position, of course, high pressurefluid from the pump will be conveyed by way of the passage 62 to themodulator sub-chamber 57 for driving the modulator toward a position ofreduced pump chamber eccentricity.

i From the foregoing it will be apparent that the present iiventionprovides a variable displacement pump control arrangement that is notonly highly sensitive for selective multi-stage pressure responsivenesswithin a large range, but also in any stage of selected or adjustedpressure responsiveness of the control valve mechanism is automaticallyadjustable for variable displacement of the pump to maintain a desiredmean pumping pressure.

It will be understood that modications and variations may be effectedwithout departing from the scope of the novel concepts of the presentinvention.

We claim as our invention:

1. In combination in control means for a variable displacement pump, acasing having a bore, a control aol valve plunger in r'said bore jectingthe valve plunger at oneend to pressure fluid from the high pressureside of the pump, a spring in said bore operative on the valve plungerin opposition to the high pressure on the valve plunger, a stemprojecting from the valve plunger past the spring, a reduced diameter`portion at the rear end of the bore, an auxiliary pressure plunger insaid reduced diameter portion, said stem being engageable by saidauxiliary plunger, and means for introducing pressure Huid into saidreduceddiameter borey behind said auxiliary plunger for thrusting saidauxiliary plunger against said stem and thereby supplementing the biasof said spring.

2. `In combination in control means for a variable displacement pump, acasing having a bore, la controlv valve plunger in said bore and meansfor directly Asubjecting the valve plunger at one end to pressure uidfrom the high pressure side of the pump, a spring in said the' highpressure on the valve plunger, a stem projecting from the valve plungerpast the spring, a reduced diameter portion at the rear end of the bore,an auxiliary pressure plunger in said reduced diameter portion, saidl.stem being engageable by said`auxiliary plunger, 'and means forintroducing pressure tluid into said reduced diameter bore behindvsaidauxiliary plunger for thrusting said auxiliary plunger against said stemand thereby supplementing the bias of said springsaid auxiliary boretghaving an inner generally axially facing shoulder against which theauxiliary plunger is` engageable as a stop toV limit movement of thevalve plunger in opposition to the spring and auxiliary plunger.

3. In a variable displacementI pump construction, a

,fr casing ring dening a modulator chamber, a modulator ring member linsaid chamber and cooperating at diametrically opposite sides withthevwall of said ring dened chamber to divide 'the space in said chamberinto opposite sub-chambers at respective diametrically opposite* sidesof the modulator between said first 4mentioned diametrically oppositesides, said modulator having therein a pump chamber within which Va pumprotor and uid impelling means are adapted to operate, casing structureenclosing the opposite faces of said casing ring and the periphery ofsaid casing ring, respective iluid inlet and outlet ports communicatingthrough said casing structure with the pump chamber, said casingstructure having a valve chamber therein, said casing structure having apassage leading from one of said sub-chambers to said valve chamber,said casing ring and said casing structure having a Huid passage leadingto said valve chamber from the other of said sub-chambers, said casingstructure having a further passage leading to said valve chamber from`said outlet port, and a valve member in said valve chamber responsiveto uid pressure through said further passage to control the ow ofpressure fluid from said further passage through said valve chamber intoselectively the passages from said sub-chambers, said passage leadingfrom said other of said sub-chambers to said valve chamber comprising inpart a groove in the outer periphery of said casing ring and said groovebeing closed at the periphery of the casing ring by the surroundingcasing structure.

4. In combination in a variable displacement pump, a casing defining amodulator chamber, a modulator adjnst ably movable in said chamber andcooperating with the walls defining said chamber to divide the modulatorchamber into sub-chambers at respectively substantially diametricallyopposite ends of the modulator, the modulator having therein a pumpchamber, a pump rotor operable in said pump chamber and having meanscooperating with the wall of the modulator defining the chamber todisplace uid through the pump chamber, uid inlet and outlet portscommunicating with the pump chamber, and means for controlling theposition of the modulator in said modulator chamber comprising: a valvechamber proand' means for directly subs vided by the casing, respectivepassages leading from said sub-chambers to said valve chamber, a furtherpassage leading from said outlet port to the valve chamber, a plungervalve reciprocable in said valve chamber and operable responsive to uidpressure communicated through said further passage to control deliveryof pressure' uid from said further passage through said valve chamberselectively to said passages that communicate with said sub-chambers, aspring normally biasing said valve plunger in opposition to the pressureof uid delivered through said further passage, said valve plunger havinga portion extending therefrom past the spring, a reciproeable plungerindependent of the spring and reciprocable relative to the valve plungerbut disposed in thrusting relation to said plunger, and means forsubjecting the reciprocable plunger to uid pressure to drive thereciprocable plunger into thrusting relation to said portion forsupplementing the bias of the spring in opposing pressure from the pumpthrough said further passage, whereby to increase the bias load thatmust be overcome before the valve plunger will shift in opposition tothe spring.

5. In a variable displacement pump construction comprising a casingstructure defining a modulator chamber having movable therein amodulator cooperating with the walls defining the chamber to divide thechamber into respective sub-chambers at substantially diametricallyopposite ends of the modulator, the modulator having therein a pumpchamber cooperative with a pump rotor for displacement of uid throughthe pump chamber from an inlet port to an outlet port communicating withthe pump chamber, the improvement which comprises: a reciprocable valveplunger, said casing having a valve chamber within which the valveplunger is reciprocable, respective passages in the casing communicatingwith an intermediate portion of the valve chamber, a pressure passagecommunicating with one end portion of the valve chamber and with theoutlet port and impressing on one end portion of the valve pressure fromthe pump and for supplying pressure through said respective passagesunder the control of the valve plunger to said sub-chambers, additionalpassages leading from the valve chamber and communicating with saidsub-chambers, a passage leading from the inlet port to the opposite endportion of the valve chamber for communication under the control of thevalve plunger with said additional passages, a spring disposed betweensaid opposite end portion of the valve chamber and the adjacent endportion of the valve normally biasing the valve toward said one end ofthe valve chamber, said opposite end of the valve chamber having areduced diameter bore portion, a freely reciprocable biasing plunger insaid reduced diameter portion, a stem on the valve adjacent to saidbiasing plunger and thrustingly engageable by the biasing plunger, and apassage leading into the inner end of said reduced diameter chamberportion for supplying iluid under pressure behind said biasing plungerto eirect valve biasing thrust of said biasing plunger against said stemsupplemental to the bias afforded by said spring.

References Cited in the le of this patent UNITED STATES PATENTS1,943,929 Rayburn Ian. 16, 1934 2,080,810 Douglas May 18, 1937 2,166,423Clark July 1s, 1939 2,238,062 Kendrick Apr. 15, 1941 2,254,103 DouglasAug. 26, 1941 2,391,323 Martin Dec. 18, 1945 2,433,484 Roth Dec. 30,1947 2,490,115 Clarke Dec. 6, 1949 2,600,632 French June 17, 19522,600,633 French June 17, 1952 2,649,739 Huferd et al. Aug. 25, 1953FOREIGN PATENTS 528,950 Great Britain Nov. 11, 1940 574,359 GreatBritain Jan. 2, 1946

